Knut Ståle Erga

Global Right Atrial Mapping Delineates Double Posterior Lines of Block in Patients with Typical Atrial Flutter

Introduction: The crista terminalis (CT) has been shown to be a barrier to transverse conduction during typical atrial flutter (AFL). However, some studies have demonstrated the presence of functional block in the sinus venosa region but not at the CT. The aim of this study was to define these regions of block in the right atrium using a three‐dimensional noncontact mapping system.

Three‐Dimensional Noncontact Mapping Defines Two Zones of Slow Conduction in the Circuit of Typical Atrial Flutter

CHEN, J, et al.: Three‐Dimensional Noncontact Mapping Defines Two Zones of Slow Conduction in the Circuit of Typical Atrial Flutter. The cavotricuspid isthmus (CTI) is a slow conduction area in the circuit of typical atrial flutter. However, conventional methods are limited by the inaccuracy of measurements of distance on the surface of the heart. The aim of the study was to define the conduction properties of the atrial flutter circuit along the tricuspid annulus by using a three‐dimensional noncontact mapping system. In 34 atrial flutter patients (30 men, 4 women; mean age 54 ± 14; 27 counter‐clockwise, 4 clockwise, and 3 both), a noncontact multielectrode array was used to reconstruct electrograms in the right atrium. Isochronal and isopotential propagation mapping was performed during atrial flutter. The conduction velocity was calculated by dividing conduction time by surface distance. The right atrium along the tricuspid annulus was divided into five regions: lateral wall, superior right atrium, septum, septal CTI, and lateral CTI. Conduction velocities were 0.99 ± 0.85, 1.67 ± 1.21, 1.58 ± 1.05, 0.82 ± 0.72 , and 1.68 ± 1.00  m/s in counter‐clockwise and 0.81 ± 0.71, 2.61 ± 1.90, 1.52 ± 0.91, 0.91 ± 0.80 and 1.91 ± 0.83  m/s in clockwise, respectively. Conduction velocities were significantly slower in the septal CTI and lateral wall than in the lateral CTI, the septum, and the superior right atrium (P < 0.05). No significant difference was found between the septal CTI and the lateral wall. Conduction within the septal CTI was slower in patients treated with antiarrhythmic agents than in untreated patients (P < 0.05). The septal part of the CTI (but not the lateral CTI) and the lateral wall are slow conduction zones in the atrial flutter circuit, and both may, therefore, be mechanically important for the development of atrial flutter. (PACE 2003; 26[Pt. II]:318–322)

A clinical study of patients with and without recurrence of paroxysmal atrial fibrillation after pulmonary vein isolation.

Patients with paroxysmal atrial fibrillation (PAF) can be treated by pulmonary vein (PV) isolation. However, the recurrence rate after this procedure is relatively high. We sought to evaluate the quality of life (QOL) of patients with PAF recurrence after PV isolation and to analyze factors related to recurrences. Seventy‐two drug‐refractory PAF patients (59 men, 13 women, mean age 52 ± 10) were included. PV isolation was based on the disappearance of PV potentials recorded from a Lasso catheter after segmental ostium ablation. Automatic foci were observed in 47 patients (65.3%) during the procedure. A mean of 3.1 ± 0.9 PVs was isolated. Patients were followed for a mean of 10.3 ± 5.1 months, during which 27 experienced >1 episode of PAF. QOL was scored from 0 (situation before ablation) to 10 (no episode after ablation) based on a questionnaire completed by 69 patients (95.8%). QOL was judged very good in 26 patients (none with PAF recurrences), better in 30 (15 with PAF recurrences), unchanged in 11 (10 with recurrences), and worse in 2 patients with PAF recurrences. Longer histories of PAF and a lower percentage of patients with automatic foci identified during the procedure were observed in the group with, than in the group without recurrences (P < 0.05). PV isolation improved QOL in patients with PAF, including in patients with recurrences. The length of PAF history and observation of automatic foci may be of importance for recurrences of PAF during long‐term follow‐up.

Identification of extremely slow conduction in the cavotricuspid isthmus during common atrial flutter ablation.

AbstractIntroduction: Complete isthmus block has been used as an endpoint for radiofrequency ablation for common atrial flutter (AF). We sought to systematically evaluate extremely slow conduction (ESC), which is easily misinterpreted as complete block. Methods and Results: We studied 107 consecutive patients (92 men, 15 women, 58 ± 11 years) who had undergone a successful AF ablation procedure. A 24-pole catheter was positioned along the tricuspid annulus spanning the isthmus. Complete isthmus block was defined as the presence of a complete corridor of double potentials along the ablation line. Activation delay time (AT), activation difference (ΔA) between two adjacent dipoles, maximum activation difference (ΔAmax), change in polarity (CP) and change in amplitude (CA) of the bipolar atrial electrogram were recorded and P-wave morphology in the surface electrocardiogram was analyzed. ESC was observed in 16 patients. Between ESC and complete block, differences were found on the two lateral dipoles adjacent to the ablation line (AT: 148 ± 17 vs. 183 ± 27 ms and 155 ± 18 vs. 170 ± 28 ms, P < 0.01; ΔA: −91 ± 22 vs. −126 ± 28 ms and −7 ± 13 vs. 13 ± 6 ms, P < 0.01). Statistically significant differences in CP were detected on the relevant dipoles (7/16 vs. 14/16 and 6/16 vs.13/16, P < 0.05). No significant difference was found either in CA or in terminal P wave positivity. Mean ΔAmax were 13.8 ± 5.0 and 27.8 ± 9.5 ms (P < 0.001) respectively in ESC and complete block. Two types of ESC, regular and irregular, were demonstrated during the ablation procedure. Conclusions: (1) ESC was observed in 15% of the patients during the AF ablation procedure. (2) The parameters of AT, ΔA, and CP may help to differentiate ESC from complete block. ΔAmax might be the most powerful indicator. (3) To verify complete block, it is essential to position the mapping catheter across the CTI in order to demonstrate the activation sequence up to the ablation line.